1. Field of the Invention
The present invention relates to improvements in the steering and operation of tracked vehicles. More particularly, the present invention relates to a method and apparatus for steering a two-wheel or track-driven snowblower thereby reducing the effort required to operate the vehicle.
2. Description of the Prior Art
Powered snowblowers have been in service for many years. There are essentially two basic types of snowblowers, a one stage and a two stage blower. A one stage snowblower usually has a sub-frame and a housing connected to the sub-frame. The housing has a front opening where the snow is taken in between spaced apart side walls. An engine is mounted on the sub-frame and an impeller is journalled into the side walls of the housing and is rotated by a direct drive mechanism connected to the engine. In a one stage snowblower the impeller is the only powered device used for collecting the snow and throwing the snow out the snowblower's snow exhaust chute.
A two stage snowblower is similar to a one stage snowblower in that it has a sub-frame with an attached housing which has spaced apart side walls and an engine mounted to the sub-frame. However, a two stage snowblower uses an auger journalled between the spaced apart side walls of the housing to collect the snow to be brought into the housing. The auger is generally a pair of opposing helical flights which in a first stage rotate to force the snow into an opening in the rear of the housing. In the second stage a fan is located near the opening which forces the snow up and out of the snow exhaust chute. Hence, the name two-stage snowblower.
With respect to both types of snowblowers, but in particular with respect to the two stage snowblowers, there have been attempts to improve the performance of the snowblower by altering certain characteristics or by adding features which will perform additional functions. Some of these improvements have related specifically to improving the steering of snowblowers. Prior to the present invention there are no known inexpensive, simple solutions to reduce steering effort and easily steer a snowblower or other hand operated tracked vehicle. Typically, the operator was left to "strong-arm" the machine in order to effect a turn. However, snowblowers can weigh as much as several hundred pounds and can thus be very difficult to turn using only human power especially for the elderly. This is usually due to the fact that most snowblowers have no provisions for turning, steering, or altering the direction of the track drive employed to move the snowblower. The wheels of a wheeled snowblower, as well as the tracks of a track-driven snowblower, are usually designed to move in a single direction--straight forward motion. However, the prior art does not address these problems and therefore there are few inexpensive, simple handling or steering devices available to improve the overall handling or steering performance of snowblowers.
An example of an attempted improvement is Thorud et al, U.S. Pat. No. 4,694,594. Thorud et al. is related to an improvement in the impeller of a single stage snowblower which has a central section which performs a snow throwing function and end sections which perform a snow collecting function to feed the snow to the central snow throwing section. Another example of an improved snowblower is U.S. Pat. No. 4,836,320 to Sundin. Sundin relates to a device for improving the turning of a handle-operated snowblower. Sundin teaches the use of pads mounted to the frame of the snowblower so that the weight of the snowblower may be tilted onto the pads and the snowblower can then be pivoted to redirect the snowblower's line of travel. While the Sundin teachings attempt to solve the problems with the prior art, the device still requires significant operator effort to shift the entire weight of the snowblower onto the pads and to then redirect the snowblower.
In addition to the type of lifting, tilting and dragging type steering apparatus disclosed in Sundin, the prior art discloses expensive and heavy duty rear-drive differentials and/or transmissions in order to engage or disengage power to the drive wheels or track on one side of the snowblower in order to effect a turn of the snowblower. The same type of turn has been accomplished in snowblowers having power-driven wheels or tracks through the use of expensive brake devices wherein a braking force is applied to one side of the snowblower so that the wheel or track on the non-braked side of the snowblower is caused to drive around the braked side of the snowblower in order to turn the machine. However, as noted, these types of devices are expensive, heavy, and usually have a relatively poor turning radius.
Another attempted handling or steering improvement to snowblowers is that disclosed in U.S. Pat. No. 4,756,101 to Friberg et al. Friberg et al. teach an apparatus for adjusting the position of the rear wheels with respect to the center of gravity of the snowblower in order to make it easier to adjust the cutting depth of the snowblower in certain snow conditions. To achieve a shift of the wheels with respect to the center of gravity, Friberg et al. teach the use of a linkage system connected to the axle on which the wheels are mounted. The axle is then pivoted with respect to the frame of the snowblower to a point where the wheels are just under or in front of the center of gravity, thereby making it easier to tilt the machine and adjust the depth of cut to be taken by the auger.
Additionally, it would be advantageous to improve the performance of the snow exhaust chute in order to prevent clogs therein. An example of this type of improvement to a snowblower is illustrated in U.S. Pat. No. 3,465,455 to Kiernan. Kiernan involves a snowblower having an auger in a housing and a fan to blow the snow out of an exhaust chute. Sometimes, when the snow is very wet and heavy, the exhaust chute can become clogged. In order to prevent clogs in the snow chute, it is advantageous to heat the snow chute in order to melt the clogged snow and thereby clear the chute. Thus, Kiernan teaches the pumping of the engine's hot exhaust gases into a jacket surrounding the exhaust chute in order to warm the snow exhaust chute.
Other examples of improvements to snowblowers are: U.S. Pat. No. 2,261,732 to O'Brien; U.S. Pat. No. 3,189,021 to Giguere; U.S. Pat. No. 4,978,068 to Eldridge; and U.S. Pat. No. Re 33,726.
Thus, while the prior art has recognized some of the limitations and problems associated with snowblowers, it is apparent that there is a need for further improvements. This is especially true with respect to the steering and the performance of such snowblowers.